Gravity fed, liquid-fuel-pilot-type oil burner



Sept. 7, 1954 R. w. DE LANcEY 2,688,362

GRAVITY FED, LIQUID-FUEL-PILOT-TYPE OIL BURNER Filed OGL-21; 195ov s shams-sheet '1 ai?, LH

di JI" INVENTOR. uP/J W. fAv/vcs Y A TTORNE Y Sept. 7, 1954 R. w. DE LANCEY 2,588,362

GRAVITY FED, LIQUID-FUELPILOTTYPE OIL BURNER Filed Oct. 4, 1950 5 Sheets-Sheet 2 W VENToR.

? 6'/ l Z 0364 ATTORNEY Sept. 7, 1954 R. w. DE L ANcEY GRAVITY FED, LIQUIDFUEL-PILOTTYPE OIL BURNER Filed 00T.. 4, 1950 5 Sheets-Sheet 5 i v INVENTOR.

v fwf/ Melancsv BY ATTORNEY Sept. 7, 1954 R. w. DE LANcEY GRAVITY FED, LIQUI-D-FUEL-PILOTTYPE OIL BURNER 5 Sheets-Sheet 4 Filed Oct. 4, 1950 Y .E OKC wmp.. E@ may Wu .m L .4,5% 1W l/ ATTORNEY Sept. 7, 1954 R. w. DE LANCEY GRAVITY FED. LIQUID-FUEL-PILOT-TYPE OIL BURNER Filed Oct. 4, 1950 5 Sheets-Sheet 5 kk. im

Patented Sept. 7, 1954 GRAVITY FED, LIQUID-FUEL-PILOT-TYPE OIL BURNER Ralph W. De Lancey, Meriden,

Conn., assgnor,

by mesneassignments, to Miller Oil Burner Company, Inc., Warren, Minn., a corporationl of Minnesota Application October 4, 1950, Serial No. 188,334 Y The present invention relates to gravity fed, liquid-fuel-pilot-type oil burners.

Gravity fed, liquid-fuel oil burners are usually operated either on an alternate high fire-pilot cycle or on a high fire-no fire cycle. In the latter, the burner is allowed to burn dry at the end of each high fire operation, while in the former, ignition is maintained between high fire periods by means of a gas or oil pilot. The oil pilot is more customarily employed.

The general practice, heretofore in use where oil pilot is employed, is to alternately feed fuel from a source at a substantially constant level at one metered rate for high fire and another for pilot, this fuel drainingfrom the metering valve through suitable passages in the bowl of the burner and at high fire forming a pool in the burner bowl. When the fuel flow rate is reduced to the pilot rate, the fuel in the burner is gradually consumed so that the burner bowl burns dry except where the pilot fuel is admitted. This fuel continues to burn during the pilot period and provides ignition for the next high nre operation. As the pilot operates over long periods, economy requires the employment of as low a low pilot firing rate as can be successfully maintained.

There is a tendency for the accumulation of carbonaceous residues in the region where the pilot is maintained, especially when operating over long periods at pilot flame. The pilot fuel is usually received in a pilot well which lls to overflowing by the fuel flowing into the burner to maintain the -pool for high fire. The pilot well residues are then submerged, and while wetting and softening of accumulated pilot fire residues facilitates the burning away of much of the same during the receding of the fuel topilot feed, all such residues cannot be so disposed of, and accumulation of unburnable residuesresults in the region where the pilot flame has operated. The difculties arising from accumulation of such residues have been greatly overcome by improved design of the burner, as, for example, in my Patent 2,423,808, July 7, 1943, but it has been impossible to so completely eliminate carbonaceous residues about the pilot as to equal the results where the cycle is of the high-fire-no-re type.

The present invention contemplates improvements in the oil burners and controls for them and contemplates an improved means for operating liquid fuel pilot type gravity fed Vaporizing burners.

In its broader aspects, thepresentinvention Claims. (Cl. 158-91) contemplates that the burner bowl, or vaporizer will have two inlets for fuel below the level to which the fuel is admitted to high fire, so that these inlets are then submerged. In the opera-v tion of the burner, with each alternate change in the rate of fuel supply to the selected rate, one or the other of the inlets is selected for the flow of fuel at the next pilot period. In some cases, the change is made vwhen going from low fire to high, while in Vother cases when going from high re to low fire. Accordingly, when the re changes from high fire to pilot at the selected inlet, the fuel in the burner is burned away and the remainder of the fuel in and about the inlets is also consumed, but in view of the fact that no fuel is coming in 'through one of the inlets, this inlet is burned dry and any carbonaceous residue there consumed in a manner similar to that customary with similar burners having a single fuel line and operated on a highfire-no-re cycle, while at the other inlet pilot fiame is maintainedbecause fuel is fedto the burner at pilot rate through that inlet. In the next cycle of operations, the fuel supply is so controlled that pilot fuel is admitted through the inlet which previously had-been burned dry and at least during pilotV operation is cut, olf from the inlet where pilot operation took place in the preceding cycle. In this manner, at each alternate pilot f-lre period, one inlet burns dry while the other one maintains Vthe pilot, and in each succeeding cycle the position vwhere pilot operation took place shifts from where itA was at the preceding pilot.

The method of operation above outlined may be obtained -by manipulation of manually controlled valves, or automatically by suitable apparatus under remote control as, for example, by a room thermostat. Where the operation is to be manuaLone can employ a constant level valve-metering valve u nit having two manually operable metering valves shiftable between off, pilot, and high re'positions. Such valves are available for operating two separate oil burners and to carry outthe above outlined process, the two outlet connections from such double metering valve unit are vconnected to the separate burner bowl inlets` above refererd to. While one such valve is closed, the other is opened for high re, then reduced to pilot, the rst remaining closed; then the first opened to high fire and when the pilot has ignited, the fuel fed through the second Valve shifted from pilot to closed position, it remains closed through the next pilot period and reopened for the next high fire, etc.

5. illustrating a hydraulic control for obtaining alternate pilot re operations and utilizing a dam to divert fuel to a favored pilot well at the respective inlets;

Figure 16 is a time diagram showing operations of the hydraulic arrangement of Figure 15;

Figure 17 illustrates a selector valve suitable for hydraulic operation and arranged to divert all the fuel to one or to the other of the pilot wells; and

Figure 18 is a diagrammatic view illustrating a form of construction employing manualy controls for obtaining pilot operations alternately at the well.

The bowl of a vaporizing pot type oil burner is shown at 20 (Figs. 1 and 2). This bowl carries a central air distributor 2| and spreader 22, and is received in a housing 23. Above the vaporizer 20 is a perforated tube 24 and the top of the housing carriesI a ring 25. These parts, together with the bariles indicated at 25 and 26 may be constructed in accordance with my Patents 2,290,544, 2,423,868, and 2,373,814. A forced draft is provided through a draft tube indicatedy at 2l and oil is received in the burner bowl through two pilot Wells A and Br. These pilot wells are close to one another but are separated by a partition or dividing wall 3l) at the same level as the burner bowl surface indicated at 3l.

The fuel is supplied to the burner from a fuel supply line 45 which is connected to a combined constant level and metering valve generally indicated at 4l. Any convenient form of constant level-metering valve construction may be used. Such combination valves have one or two outlets such as the one shown at 42. Various forms of metering valves are used in such constructions. In some cases the metering valves are biased toward closed position and in other cases toward an open position. For convenience, the movable metering valve member 43 is of the type which is biased toward closed position and shifted toward open position by a bimetal thermostat element indicated at 44 asset forth more in detail in my Patent No. 2,359,024. Such metering valve stem has a small hole 45, slightly below the upper surface of the oil as indicated in Figure 7, to supply fuel for pilot.

The bimetal operator 44 for the' metering valve 43 is energized by heat from the resistor 46 connected to the usual control circuit Which includes transformer T, room thermostat 4l and limit switch 46. The constant level valve mechanism in valve 4I keeps the oil level at substantially the constant level indicated, and when the bimetal operator 44 for the metering valve is cold, fuel flows through hole 45 to maintain pilot at all times. When the control circuit is closed, the bimetal warps and opens the metering valve to the high fire position in the usual manner, so as to supply fuel at a high rate for high re.

In the construction shown in Figure 7, the end of the bimetal member 44 carries a pawl 49 cooperable with a ratchet wheel 5l! carried on a shaft 5l, so that each time the heater 46 operates the bimetal element 44, the ratchet and pawl mechanism advances the shaft 5I one tooth. The shaft 5I operates a cam wheel 52 having deep notches indicated at 53 alternating with shallow notches indicated at 54. These notches are equally spaced and of the same number as the teeth on the wheel 55. They form a cam surface on which bears a contact carrying spring 55. This spring is opposite a xed contact 56 connected to thetransformer by wiring indicated at 5l. The movable contact 55 is connected by wire 58 with heater coil 59 so as to provide a circuit in parallel with the heater circuit 46 and adapted to be opened or closed, depending upon whether the movable contact 55 is in the deep or shallow notch of the cam 52.

As shown in Figures 4 and 7, the switch elements 55, 56 are in the open circuit position and the heater 59 is deenergized. The heater 59 is close to a bimetal warp element 55 whose free end carries a vertical movable plunger 6l. When the coil 59 is cold, the plunger is held up as shown in Figure 4, and when the coil 59 is heated, the warp bar 66 forces the plunger 5l down as indicated in Figure 5. The plunger 5l is carried in a valve housing `62 and enters into a chamber 63 in this housing.

This chamber 53 has a bottom connection 64 coupled to a tube 55 whose other end is secured to the outlet connection 42 from the metering valve. The chamber 63 includes a, lateral drilling 66 from the left and a lateral drilling 5l from the right. The drilling 65 is slightly lower than the drilling 6T so that the bottom of the drilling 61, Where it intersects the drilling 65 and inlet opening 54' forms an obstruction lll, at an elevation above the bottom of the left drilling 56. The left drilling E55 is intersected by a horizontal outlet passage ll, while the rightehand drilling 6l is intersected by a horizontal outlet passage l2. The passage ll is at a lower level than passage 'l2. The passages ll and l2 lead toward the burner and are connected to the pilot wells A and B by tubes i3 and '14. The tubes 'll and 12 are provided with vents as indicated at l5 `and 16, so that fuel can rise and fall in accordance with the hydraulic head existing.

A mounting bracket 84 is secured to a plate 3l adapted tobe placed over the door opening of the furnace. The bracket 85 has an arm 82 which supports constant level-metering valve assembly 4l, a second arm 83 which supports controls gen-v erally indicated at 84 and also is formed into a box-like chamber or air chest 85 into which the vent tubes 'l5 and 'l5 enter. This chamber is open at the leftv as indicated in Figure 2 and a motor operated blower unit S6 is secured to the housing so as to provide a blast of air into the housing 85. The air duct 2l interconnects the pressure chamber 85 and the burner so that air may be blown from the chamber 85 through the duct to supply the burner with air for combustion. The tub-es 'E3 and 74 pass through this duct as indicated in .Figures l and 2. The selector valve 62 is secured to the front well of the chamber 85 by a bolt as indicated at Sl.

In the operation of burners such as described, the blower 86 is intended to operate continuously so as to provide continuous draft to the burner. The burner itself is adapted to burn liquid fuels of the catalytic cracked type having high carbonaceous residues, but difcult to burn in pot burners as discussed in my patents above referred to, and it is contemplated that such a fuel vwill be supplied to the present equipment.

If it is assumed that the parts' are in the position shown in Figures 4 and 7 of the drawings, and the burner is operating at pilot, there will be a pilot llame in the pilot well A, which is favored'v because of the fact that it is connected to the lower side of the selector valve chamber which is fopen to the fuel supply. The fuel level is as shown in Figure 4. At this time the valve 6,I .is up so that at pilot operation, all thefuel owingthrough the closed metering valve will go to pilot A. At this time, as Vshown in Figv ure 7, the pawl` is down and the switch ele-A ment 55 is `resting in a high notch 54 vso that the .switch 55, .5.6 is open `and the bimetal `element 60 cold.

If there is a demand for heat, the metering valveheater will cause the bimetal .44 to bend upwardly and. gradually open the metering .valve to-increase the Aflow rate to the high rate. This opening .takes a measured length of time so 4that the flow is not immediateand sudden. During the lifting of the bimetal lill, the paWl 4a will be lifted up and the index wheel 5!! shifted pne tooth. 4This shiftwill cause the end of contact 55 to enterinto a deep notch 53 and close the circuit at 55, 55, thereby energizing the heater 59. -This -is a relatively slow acting heater and it will heat the bimetal Si) .causing it to bend down and lower the plunger 6 I. During the time consumed for these operations, the oil yat higher rate of feed will fill the pilot well A to a level high yenough to cause it to flow over the obstruction 'IG and down through rpipe l2, 'I4 to pilot well B` The timing is such that oil will have risen out of the pilot wells so thatcombustion will take place in or near both pilot wells, so that the shifting of plunger valve 6| down to the position of Figuredoes not cut off or aifect the high nre operation. This high fire operation will continue as long `as the heat is demanded, and for this entire period both heaters 46 and155 will hold the valvestem 123 up and the valve stem ,el down.

When the heating required is satisfied, and the heater. @.5 deenergized, the metering ,valve goes to closed or pilot position and the pawl i9 drops down below a tooth. This does not anect the circuit through heater 59 so that the plunger 6| will continue to be held down. Fuel in the burner bowlwill be consumed and all the fuel in pilot well A and the line leading to it will be burned away. Fuel, however, will run down through line 12, l so that pilot is maintained in pilot well B. Air from air chest 85 will .enter tubes 'I5 and I6 and pass through the pilot wells to provide air for combustion.

lThe next time there is ademand for heat, the metering valve is slowly opened and fuel flows through the fuel lines to pilot well B. This op. eration of the metering valve will shift the index wheel 5G one more tooth and will shift the ca m 52 to a position to open the circuit for heater `coil 59 so that vthe bimetal S5 will cool and plunger 6I will rise. Its movement is ineffective at this time for the burner is operating at near high fire and fuel can flow down through both lines.

At the end of this Second high nre operation, however, the fuel in the burner bowl will be oo nsumed as well as that in pilot well B and the line leading to it. Pilot operation, however, will be maintained in pilot well A.

This cycle of operation continues indenitely and after each pilot operation in one well, there is a pilot operation in the other well and the earbonaceous residue which was left from the previous pilot operation will be consumed when that well is burned dry. The burner, therefore, operates so far as burning away earbonaceous residues out of the pilot well is concerned, in the i same manner as a similar dry well burner ignited electrically or by torch.

With thearrangement shown in Figures 4 to '1, .the disabling Qfthe Selector valversuit 017 removal -of plunger .5I reduces the operation of the burner to a condition where there is continuous operation in the'favored pilot well, namely, pilot well A, for in such cases, during pilot op.- eration, as long as pilot A can operate, it will receive all ,the pilot fuel. Under such circumstances, should burner operation continue until that pilot well .is clogged orseriously impaired by reason of accumulated earbonaceous residues, the fuel will accumulate in the chamber of the selector valve and arise to a suciently high level to overflow the dam and pass into well B, start ignition there and automatically transfer pilot operation to well B. Operation will continue from well B until the residues have been burned away from well A sufficiently to permit it to dominate and take all the pilot fuel.

In the arrangement shown in Figure .'la, all the parts are generally like those shown in Figures 4 to 7, except that the cam wheel 52 is advanced or retarded one tooth, andthe bimetal element 61| is reversed so as to be bent up when heated instead of down. Then theselector valve is normally in closed position of Figure 5 when the heater59 .is cold and is shifted to the open position of Figure 4 when the heater 59 is energized. The arrangement -shown in Figure '7a does not, however, function the Same as shown in Fig-ure 7 in case the selector valve is disabled for then the valve stem 6| is biased down and the fuel would always flow down through pilot line '12, .M topilot well B which would operate each pilot period.

in. the construction -shown in Figures 8 to 14, inclusive, the same structures are used, except for- -the selector valve and its controls and corresponding reference characters are applied to these figures without specific enumeration of the same. Here lthe control circuit having a transformer room thermostat 4l and limit switch 48, is connected by wiring I-llI and |02 with a heater coil yIIlfS below a bimetal member |64. The bimetal element I-{Mis connected by a wire with a small synchronous motor |66 -and this motor is connected by wire Iil'I Vwith the transformer lead vIUI. The bimetal element m4, when in the pilot position, engages a contact |08 connected by wire I09 with the wire |02 so that the circuit to the synchronous motor is completed, except -for the opening at the room thermostat Il or at the limit switch 6.5. When the circuit through these is closed, the motor |06 is energized. V'This motor through reduction gearing in the housing IIil drives a shaft III at a slow speed, for example Mrs-R. P. M. The motor IE6 and gearing housing I -I'Ilvare mounted on top of a selector valve casing II-2. This casing has a vertical bore IIS Which receives a vertical valve stem H4. This valve stem is freely rotatable in the bore and has a non-circular opening IIE into which the flattened portion of the shaft I I I enters as 'shown in Figure 13. The valve Amember |I4 -is provided with an enlarged head II having two cutouts or notches indicated at I 96a and Ilb. The motor turns the member IIS in a clockwise direction as indicated in Figure 14. An insulating plunger VI Il carried in an insulated support IIB is urged against the valve head IIS by a spring ||9 carrying a contact |2il cooperating with contact |2I connected to the transformer by the wire |22. The spring contact I I9 is connected by wire |23 with the wire |l5.

The circuit through thecontacts |20-I2I `is Open .at .the andai .a cycle as Shown in Figure 9 14, but when Vthe thermostat calls for heat, the motor starts into operation and during the time 'it takes the bimetal element |84 to open the circuit at |58, the motor |06 has turned the stem the plunger |I1. This will close the circuit at I20|2| and provide a running circuit for the motor |56 until the valve member IUI is turned one-half a revolution when the plunger I I1 drops into the cutout IIBa. This will stop the motor,

the starting circuit having previously been opened by the bimetal |04.

The valve member I II is open at the bottom as indicated at. |22 so as to receive fuel delivered to the valve casing I I2 through piping |23. The lower end of the valve stem has a cutout portion as indicated at |25 adapted to deliver oil to the left or to the right, depending upon the position of the valve stem. In the drawings, it is shown as delivering oil to the left where it can flow through a passage |26 in the casing to a lter receiving chamber |21. This filter chamber communicates with the oil line 13 leading to pilot A.. Diametrically opposite to the passage |2|5 is a similar passage I 28 leading to a filter chamber |29, which, in turn, communi-v cates with the pipe 'I4 leading to pilot B. The filter chambers are closed by plugs |35 and bridging strap I 3|. The oil lines` are provided with vents |32, |32 the same as those above described, and these enter the air chest |35 as previously set forth.

In the arrangement shown in Figures 8 to 14, the cycle of operations is similar to that above described. Here pilot fuel flows to pilot well A when the parts are in the position shown and when a high re operation is to be commenced, the synchronous motor |55 is first set into operation to close its running circuit and shortly thereafter the bimetal |04 opens the metering valve 43 to allow oil to flow at high rate for highl re. This high flow rate oil is delivered to pilot A. After the valve I It is turned somewhat more than a quarter of a revolution, it will deliver oil to both lines and to both pilot wells so that for a time oil is flowing into the burner through both pilot wells. When the valve IMI has been turned through the full 180, cil flow will have been cut off to the line leading to pilot A and all the oil will be delivered to pilot B. The synl' chronous motor |55 will thenhave stopped and the high fire operation will continue until the control circuit is opened. The bimetal |05 will then cool and allow the metering valve to close `I I4 far enough to pass the cutout IItb beyond I so that pilot fuel will then flow down through pilot B. Operation will continue at pilot B until the bimetal |54 is again heated to start a new high fire cycle, whereupon the operation will continue at pilot B, and shift to pilot A in the manner above described.

In Figures and 16 a form of construction operating in a hydraulic manner is diagrammatically shown. It employs an arrangement having two oil levels with dam and shift valve of the type shown in Figures 1-7, but .has no electrical operating parts. Here the oil inlet |553 is assumed to be connected to a constant level-metering valve arranged to provide fuel at high rate for high re and pilot rate for pilot fire. Such a valve mechanism may, for example, be manually controlled or of the remote controlled thermostatic type, or the solenoid type.

Figure 15 shows the parts in position for delivering pilot fuel through oil line |5I to pilot B. The selector valve member |52 is down, as is corresponding member 6I (Fig. 5). Oil comes in through supply line I 55, overflows the obstruction |53, and asshown by the full line arrows supplies pilot B. In its passage to B it flows over the iioor |54 of a float chamber |55. This chamber accommodates a float |55 which is in lowered position.

When the flow rate is increased oil flows through the chamber passage I5I, pilot well B, and rises in the burner bowl to the high nre operating level. This causes the float |55 to rise. The float is connected to a bell crank |51 rotatably carried in a -shaft |58. The bellcrank carries a pawl |59 cooperable with a ratchet wheel |55 keyed to the shaft so that the shaft is turned a corresponding'amount, here 1/8 of a revolution.

The shaft |53 carries a cam |6I which in the form shown has four high spots |5|a and four low spots I5|b. In the position shown a high. spot |6|a bears on the upper end of the valve member I 52 and forces it down against a lifting spring |62. Turning the shaft |55 one tooth turns the cam so that a low spot I5|b is opposite the valve member |52 and the spring lifts it. This permits oil to enter passage |53 at lower level than the top of obstruction |53 and pass to the burner through pipe and pilot well A. Before this valve |52 will have been fully opened, oil may have flowed from B to the burner bowl and back up pipeline |55, but this is of no importance in the cycle.

On reduction of the ilow rate to the pilot rate, the oil will be consumed in the burner bowl, the

, pilot Well B burned dry and the float allowed to the cam so that the next high spot will engage valve member |52 and close the selector valve. High fire continues and in the next pilot operation well A is burned dry and well B is the pilot well.

The sequence of shifter valve, float andvpilot operations is illustrated in Figure 16.

In the arrangement shown in Figure 17, the

selector valve resembles that of Figures 8 to 14.

The fuel is delivered from the metering valve to a chamber |10 in a valve body |1I. This body has two outlets |12 and |13 adapted to be connected as before to pilot wells A and B. The chamber |10 receives a vertically reciprocable valve member |14 with outlets |15 and |15 at two levels. The valve member is biased upwardly by a spring |11 against a cam |13 similar to cam I6| and operated by a similar float and ratchet and pawl mechanism.

When the valve member |14 of Figure 17 is pressed down, as shown, fuel flows through the outlet |13 only and when released the fuel flows through outlet |12 only. There is also a period during which fuel flows through both outlets. In this arrangement the float is in one fuel line (for example the one leading to pilot B), but it rises in response to fuel flowing at high fire rate into pilot A because of the overflow into B and reverse flow up through pipe |13. It lowers whenever the burner consumes the fuel to reduce its level.

.Figure 18 illustrates diagrammatically another form of construction in. which alternate pilot operation can be carried. out. Here constant level-metering valve |80 of the conventional type having two metering'valves |81, |82, capable of individual control to high fire, pilot, or olf positions. Such valves may be manuallyk or thermally operatedand are in use for controlling from one constant level valve fuel flow to one or the other or both burners of cook stoves, ovens and the like. Here one metering valve such as IBI is connected to pilot Well A, While metering valve |82 is connected to pilot; wellV B. As each has a fully open position, a pilot position, and anY oi position, one can shift pilot operation from one pilot well to they other at will.

Since it is obvious that the' invention may be embodied in other forms and constructions within the scope of the claims, I wish it to be under'- stood'. that the particular forms shown are but several ofV these forms', and various modifications and changes being possible, I do; not otherwise limit myself inany way with respect thereto.

What is claimed is:

1. A vaporizing, gravityl fed, pot type, liquid fuel burner comprising aV vaporizer' having. two separated. pilot wells depressed at4 the bottom of thepot, each provided with an inlet, a source of substantial-carbcnaceous-residue liquid fuel at a substantially constant level higher than the pilot wells and suflicient to producey in the vaporizer a pool of fuel atA substantially said higher level; means to regulate flow from said source at either a low rate for pilot operation or at a high 'rate for high fire operation', means operable when the flowv ratefis atztheslow rate Jto-direct fuel from the said flow regulating meansv to the inlet of a selectedone of the-pilotxwells, whereby uponcontinued pilot operation carbonaceous; residues are accumulated therein, and upon subsequent increaseof rate to continue iiow to the samewell, means, effective after a lapse of timeA after the initiation of` fiow at the high firing rate'sufcient to:l fill the first well, coverresidues therein with liquid fuel andl cause fuel to` overflow into the secondv well, for. redirectingv the' nowA of fuel to theinlet. of the'second well andl for cuttingv off flow of` fuel to the first well, whereby, upon re,- duction of flow into the second well to the pilot rate, the fuel in the burner andthefirst well, together with carbonaceous residues therein, are consumed. and ignition is maintainedi by fuel in the second pilot well.

2; A1 vaporizing, gravity fed, pot type, liquid fuel burner comprising; a vaporizer havingV two separated pilotl wells. depressed atv the bottom of the pot, each provided with an-inlet a source of substantial-carbonaceous-residue liquid fuel at a; substantially-constant level higher than the pilot wells and Sufficient to produce in the'vaporizer a pool of fuel at: substantially said higher level, remote controlled, electrically operated means to regulate flow fromisaidsourceat either a lowrater for pilot operation or at a high rate for high fire operation, meansV operable when the ow rate is at the low rate: to direct fuel from the saidk iiow regulating means to theV inlet of. a selected one of the pilot wells, wherebyl upon continuedy pilot operation carbonaceousv residues' are accumulated therein, and upon subsequent. increase ofrate to.continueflow tothe same well, electrically timed means, effective after a. lapse of`time' after the initiation of iiow at' the high firing rate sufficient to fill the first' well, cover residues therein with liquid fuel and cause fuel to^overow into the-second'well, for redirecting the flow of fuel to the inlet of the second? well and for cutting off iiow of fuel to the first well. whereby, upon reduction of iiow into the second well to the pilot rate, the fuel in the burner and the rst well, together with carbonaceous residues therein, are consumed and ignition is maintained by fuel in the second pilot well.

3-. A vaporizing, gravity' fed, pot type, liquid fuel burner as claimed in claim 2, wherein the electrically operated flow regulating means includes a heater controlled, bimetallic valve actuator and the timing means includes a delayed action device in. parallel with the heater.

4. A vaporizing, gravity fed', pot type, liquid fuel burner as claimed in claim 2, wherein the electrically operated flow regulating means includes aY heater controlled, bimetallic valve actuator andthe timing means includes a. motor inv parallel'. with the heater, the motor having a starting circuity opened by thev bi'metallic. operator and a self established running circuit automaticallyr openedv after a` predeterminedr number of revolutions of themotor, and a motor driven valve stopped in either of two positions in one of which it admits fuel to but one well inlet and the other of which it' admits fuel to the other well inlet only.

5. A vaporizing, gravity fed, pot type, liquid fuel. burner as claimed in claim 2, wherein the electrically operated flow regulating means in'- cludes. a heater controlled, bimetallic valve. actuator and the timing means includes, a second heater, acycling switchV operated by the bimetallic valve operator for connecting the second heater in parallel with the rst on alternate actuation of the bimetallic valve operator, a second valve operated by the second heater and disposed in the passages leadingto the said selected pilot well, to open and' close the same, the passage to the other pilot well being at all times open but including an obstruction to fuel flow at an elevation which diverts fuel at the low iiringfrate through the lastmentioned valve when the latter is open.`

6; A vaporizing, gravity fed, pot type liquid fuel burner comprising a vaporizer having two separated pilot wells depressed in the bottom' of the pot and each provided with an inlet, a source of substantial-carbonaceous-residue liquidv fuel at a level higher than the pilot wells and suflicient to produce in the vaporizer a pool of fuel at'substantially said higher level, means to regulate flow from said source at either a low rate for pilot operation or at a high. rate for high fire operation and having a single outlet, a two position flow selector valve having an inlet receiving'fuel from the outlet of the flow regulating means and two outlets, one connecting with each well so that fuel may be directed to a selected well and during continued pilot operation thereat residues are accumulated, which are covered over by fuel upon subsequent increase of flow rate to that well, operating means for the flow selector valve, effective after a lapse of time after the initiation of the high firing rate sufficient to ll the firsty well, cover the residues therein with liquid fuel and cause fuel to overflow into the second well, for changing the valve position to redirect the flow of fuel to the inlet of the second well and cut off flow of fuelv to the first well, whereby, upon reduction of flow into the second well to the pilot rate, the fuel in the burner and the rst well, together with carbonaceous residues'therein, are consumed and 13 ignition is maintained by fuel on the second pilot Well.

7. A vaporizing, gravity fed, pot type liquid fuel burner as claimed in claim 6, wherein the flow selector valve includes a vertically reciprocatory valve stem.

8. A vaporizing, gravity fed, pot type liquid fuel burner as claimed in claim 6, wherein the iiow selector valve includes a vertically reciprocatory valve stem in the passages leading to one well and having in the passage to the other well an obstruction to liquid now which diverts fuel through the selector valve when open.

9. A vaporizing, gravity fed, pot type liquid fuel burner as claimed in claim 6, wherein the flow selector valve includes a rotary valve which interrupts flow to one well or to the other.

10. A vaporizing, gravity fed, pot type liquid fuel burner as claimed in claim 6, wherein the regulating means includes a bimetallic thermostat and an electric heater for the thermostat, and the ow selector valve operating means includes a switch in parallel with the electric heater.

11. A gravity fed liquid fuel burner having alternate high fire operation and low re or pilot operation, comprising a source of liquid fuel at a substantially constant level, flow rate control means for controlling the rate of ow of fuel from the source at either a low rate for pilot or at a high rate for high fire, a vaporizing, pot type burner bowl adapted to contain at high fire a consumable pool of liquid fuel and having two fuel inlets below the level of the source, means operative without effecting cessation of now to the bowl for intercepting flow of fuel to one burner bowl inlet while diverting it to the other bowl inlet so that upon burning away the pool of fuel in the bowl consequent upon lowering of flow rate to the pilot rate, pilot combustion is maintained at said other inlet, while at the rst inlet the burner bowl is burned dry, and means to recycle the intercepting and diverting means once for each high re operation of the control means to alternately supply the inlets with pilot fuel.

12. Oil burning apparatus comprising a source of liquid fuel at substantially a constant level, a metering valve controlling the rate of flow from the source, biased toward a low fire position and r movable to a high re position, an electrically energizable metering valve operator having a remote control circuit, a fuel drain from the metering valve having a receiving portion and a discharging portion, the latter having two branches,

a second circuit including a switch sequentially controlled by the metering valve operator and in parallel with the first circuit, said second circuit including an electrically energized second valve operator, a second valve means receiving all fuel from the receiving portion of the fuel drain and transmitting it to one only or both of the discharge portions and including a movable member operated by the second valve operator on alternate energizations of the metering valve operator to close on" a selected branch so that the fuel must drain through the other branch, and a burner having a vaporizing pot receiving the discharge from both passages.

13. A va-porizing, gravity fed, pot type, liquid fuel burner comprising a vaporizer with two separated pilot wells depressed in the bottom of the pot, a source of liquid fuel at a substantially constant higher level to produce in the vaporizer a pool of fuel at substantially said higher level, a

14 metering valve for regulating fuel flow from said source at either a low rate for pilot operation or at a high rate for high nre operation, means forming a biforked passage connecting the metering valve and the pilot wells, flow control means,

effective at the pilot now rate to direct the fuel through one only of the passages to one of the pilot wells and for directing the fuel to the same well on increase of the firing rate, so that it overflows in the vaporizer into the other pilot well, and for thereafter directing the fuel at the high .firing lrate through the other passage and interrupting flow through the rst passage so that upon subsequent reduction of iiow rate the fuel remaining in the rst well is completely consumed while pilot operation is continued in the second well, iiow control means including a movable valve member, and means eifective after a lapse of time after initiation of ow at the high rate for actuating the movable valve member to redirect the fuel iiow.

14. In a liquid fuel heating system, in combination a liquid fuel supply means including a fuel flow rate control valve having a high rate for heating and a low or pilot rate and alternately shiftable back and forth therebetween, a vaporizing, pot type burner bowl having two fuel inlets and adapted when supplied with fuel at the high firing rate to burn it from a pool, and means cyclically controlled with the shifting of the flow rate control valve for directing the fuel when flowing at the low or pilot rate to first one bowl inlet and then after each intervening high re rate of flow to the other sothat the one not supplied burns dry, while at the one supplied a pilot is maintained.

l5. A vaporizing, gravity fed, pot type, liquid fed burner comprising a vaporizer with dual pilot wells depressed in the bottom of the pot, a source of liquid fuel at a substantially constant higher level to produce in the vaporizer a pool of fuel at substantially said higher level, a metering valve movable between positions, in one of which the fuel flows at a low rate for pilot operations and in the other of which the fuel flows at a high rate for high nre operations, the metering valve having a single outlet, a fuel diversion valve accepting fuel from the metering valve outlet and having two outlets each connected to one of the pilot wells and a movable member operable between two positions in one of which it obstructs iiow to one of the pilot wells at both rates of flow without interfering with flow to the other, the diversion valve also having passages to allow flow to said other Well.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,944,593 Chadwick Jan. 23, 1934 2,111,141 Dalen Mar. 15, 1938 2,290,544 De Lancey July 21, 1942 2,366,706 Breese et lal Jan. 9, 1945 2,375,347 Castle et al May 8, 1945 Y 2,464,699 Logan Mar. 15, 1949 2,476,701 Cochran July 19, '1949 2,524,139 Resek Oct. 3, 1950 FOREIGN PATENTS Number Country Date 805,880 France Sept. 7, 1936 473,230 Great Britain Oct. 8, 1937 478,780 Great Britain Jan. 25, 1938 

